【作者】 顾民；

【导师】 吕伟； 南发俊；

【作者基本信息】 华东师范大学 ， 有机化学， 2012， 博士

【摘要】 茉莉素(Jasmonates, JAs)是一类来自于氧脂素并具有环戊烷酮结构的植物激素,在调控植物整体防御能力,尤其是抗虫性,抗病性和抗伤害方面以及在调控植物的生长发育方面是必不可少的。一种由CORONATINE INSENSITIVE1(COI1)基因编码的F-box蛋白是茉莉素调控植物育性和抗性所必需的。COI1蛋白与多种蛋白相互作用形成的SCFCOI1E3泛素连接酶复合体负责茉莉素的所有应答反应。SCFcon复合物能够识别茉莉素的转录抑制因子-JAZ蛋白。SCFcoI1复合物在茉莉素作用下与JAZ蛋白结合后,使JAZ蛋白泛素化,进而通过26S蛋白酶体降解,开启基因表达,产生茉莉素相关的生物效应。茉莉酸的活性形式JA-Ile或其立体结构类似物一冠菌素(COR)能够促进SCFcoI1与JAZ蛋白的相互作用。因此,推测SCFcoI1复合体上具有结合JA-Ile/COR的位点,SCFcoI1复合体有可能是茉莉素的受体。活性导向的蛋白谱技术(ABPP)是一种非常有效的研究功能蛋白组学的化学策略。它利用活性导向的探针分子特异性的标记活性蛋白,从而使靶蛋白的示踪和纯化,以及研究蛋白-蛋白间相互作用成为可能。本论文第一部分运用活性导向的蛋白谱技术(activity-based protein profiling, ABPP),根据对茉莉素构效关系的分析以及COI1蛋白与茉莉素相互作用的分子模拟,设计合成了一系列光亲和探针分子,经过全面的生物活性检测,发现探针分子PACOR具有最好的生物活性,它能够特异性地直接结合COI1蛋白,首次成功证明了COI1蛋白能够直接结合茉莉素的活性形式JA-Ile/COR,从而确证了COI1蛋白是茉莉素的受体。茉莉酸—异亮氨酸偶联物(JA-Ile)作为茉莉素的活性分子形式,对于SCFcoI1复合物与JAZ蛋白结合以及SCFCOI1-JAZ复合物的信号传导是必不可少的。研究发现JA-Ile具有多种构象,真正起作用的活性构象是(+)-7-iso-JA-Ile,而冠面酸(CFA)与不同氨基酸的偶联物(CFA-AAs)的构象与(+)-7-iso-JA-Ile完全一致。论文第二部分设计合成了一系列CFA与各种不同氨基酸的偶联物(CFA-AAs),通过生物活性测试从中筛选出具有最好活性的CFA-AA分子—CFA-Ile,并且以CFA-Ile为基础合成了光亲和探针,为进一步阐明其作用机制和模式打下基础。更多还原

【Abstract】 Jasmonates (JAs) are a class of plant hormones, which are derived from oxylipin and characterized by a cyclopentanone structure. JAs are indispensable in plant defense responses and aspects of plant growth and development. An Arabidopsis coronatine insensitive1(COI1) gene encodes an F-box protein required for JA-regulated plant fertility and defense. COI1interacts with multiple proteins to form the SCFcI1E3ubiquitin ligase complex, which is required for all JA responses. The SCFcoI1complex recognizes JA transcriptional repressors called jasmonate ZIM-domain (JAZ) proteins and targets them for subsequent degradation by the26S proteasome in the presence of the hormone. In addition, physical interaction of SCFCOI1with the JAZ proteins is promoted by a bioactive isoleucine-conjugated form of jasmonic acid (JA-Ile) or its stereochemical mimic, coronatine (COR). These results suggest that the SCFCOI1-JAZ complex is the site of JA-Ile/COR perception and that COI1is likely to function as a receptor.Activity-based protein profiling (ABPP) is a valuable chemical strategy for the functional proteomics, which utilizes the activity-based probes (ABPs) to specifically label the active proteins, and it makes the tracing, purifying of the target protein and the study of the protein-protein interaction to be reality.The first part of this dissertation is the application of ABPP in the study of JAs receptor. We designed and synthesized a series of photoaffinity probes of jasmonates based on analysis of JAs structure-activity relationships and molecular modeling of the interaction between COI1and JAs. Among them, PACOR exhibited the most significant biological activity in inhibiting root growth, promoting accumulation of JA-responsive proteins, and triggering COI1-JAZ1interaction in Arabidopsis seedlings. Our results had shown that PACOR can bind with COI1directly. It demonstrated that COI1functions as a receptor for JAs.Jasmonoyl-isoleucine(JA-Ile) is a bioactive molecule of Jasmonates. It is essential for the interaction between SCFCOI1and JAZ proteins and perceived by the SCFCOI1-JAZ complex. Recent studies had shown that JA-Ile have several stereoisomers,(+)-7-iso-Jasmonoyl-L-isoleucine is the endogenous bioactive jasmonate. The stereostructure of conjugates of coronafacic acid (CFA) with amino acids (CFA-AAs) is identical to (+)-7-iso-Jasmonoyl-L-isoleucine stereoisomers. In the second part of this dissertation, we designed and synthesized different kinds of conjugates of CFA with amino acids (CFA-AAs). Among them, CFA-Ile exhibited the most significant biological activity. By using the photoaffinity probe of CFA-Ile, we tried to disclose the mechanism of action of CFA-AAs.更多还原